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Encryption is a process that employs a mathematical algorithm to scramble digital content so that it becomes unintelligible; decryption uses a different but related algorithm to unscramble it. In most cases, the security of encrypted information comes not from the algorithm, which is publicly known, but from a number -- called a key -- that is used with the algorithm to encrypt or decrypt the information. Decryption without the correct key is extremely difficult. Key length is measured in bits, and in general, longer keys provide better protection.
In symmetric key cryptography, the same key is used for both encryption and decryption. Asymmetric cryptography (also known as public key cryptography) uses two keys, one public and one private. To encrypt a message for someone, you need the recipient's public key, which is freely distributed. When they receive your message, they use their private key, which is kept secret, to decrypt. This technology is already in wide use -- every time you log onto a secure server on the Internet, this is the method used to keep your communication confidential. Digital Rights Management | An Interview with Scott Dinsdale |
